Several lines of evidence suggest a monoaminergic role in the pathophysiology of hypofrontality in schizophrenia. Recently, we observed that apomorphine, a direct dopamine agonist, increased prefrontal cortex (PFC) blood-flow (Xe-133 rCBF) during the Wisconsin Card Sort (WCS), a PFC- linked task. To further explore the role of monoamines on cerebral function we conducted a double-blind placebo controlled cross-over study of the effects of .25 mg/kg dextroamphetamine on cerebral blood flow (CBF) as determined by Xe-133 dynamic performance of the WCS and a simple control task. Subjects included 10 patients with chronic schizophrenia who had been stabilized for six weeks on .4 mg/kg haloperidol.